Function RM_CreateCommand

app/redis-6.2.6/src/module.c:880–923

Register a new command in the Redis server, that will be handled by * calling the function pointer 'func' using the RedisModule calling * convention. The function returns REDISMODULE_ERR if the specified command * name is already busy or a set of invalid flags were passed, otherwise * REDISMODULE_OK is returned and the new command is registered. * * This function must be called during the in

 *                        though it's not a write command.  
 */
int RM_CreateCommand(RedisModuleCtx *ctx, const char *name, RedisModuleCmdFunc cmdfunc, const char *strflags, int firstkey, int lastkey, int keystep) {
    int64_t flags = strflags ? commandFlagsFromString((char*)strflags) : 0;
    if (flags == -1) return REDISMODULE_ERR;
    if ((flags & CMD_MODULE_NO_CLUSTER) && server.cluster_enabled)
        return REDISMODULE_ERR;

    struct redisCommand *rediscmd;
    RedisModuleCommandProxy *cp;
    sds cmdname = sdsnew(name);

    /* Check if the command name is busy. */
    if (lookupCommand(cmdname) != NULL) {
        sdsfree(cmdname);
        return REDISMODULE_ERR;
    }

    /* Create a command "proxy", which is a structure that is referenced
     * in the command table, so that the generic command that works as
     * binding between modules and Redis, can know what function to call
     * and what the module is.
     *
     * Note that we use the Redis command table 'getkeys_proc' in order to
     * pass a reference to the command proxy structure. */
    cp = zmalloc(sizeof(*cp));
    cp->module = ctx->module;
    cp->func = cmdfunc;
    cp->rediscmd = zmalloc(sizeof(*rediscmd));
    cp->rediscmd->name = cmdname;
    cp->rediscmd->proc = RedisModuleCommandDispatcher;
    cp->rediscmd->arity = -1;
    cp->rediscmd->flags = flags | CMD_MODULE;
    cp->rediscmd->getkeys_proc = (redisGetKeysProc*)(unsigned long)cp;
    cp->rediscmd->firstkey = firstkey;
    cp->rediscmd->lastkey = lastkey;
    cp->rediscmd->keystep = keystep;
    cp->rediscmd->microseconds = 0;
    cp->rediscmd->calls = 0;
    cp->rediscmd->rejected_calls = 0;
    cp->rediscmd->failed_calls = 0;
    dictAdd(server.commands,sdsdup(cmdname),cp->rediscmd);
    dictAdd(server.orig_commands,sdsdup(cmdname),cp->rediscmd);
    cp->rediscmd->id = ACLGetCommandID(cmdname); /* ID used for ACL. */
    return REDISMODULE_OK;
}

/* --------------------------------------------------------------------------
 * ## Module information and time measurement